- This topic has 12 replies, 6 voices, and was last updated 9 years, 1 month ago by
.
-
Topic
-
[size=3]This is my very first post on this website, I just joined a few minutes ago.
I have a 1994 Isuzu Trooper 3.2L V6 SOHC with 207K miles. This model was sold in the US. These trucks are known to last very long and I personally know of a few which are approaching 300K miles pretty much trouble-free with nothing more than basic maintenance.
So, here’s the story. I have been experiencing poor fuel economy (11 mpg average – when the expected average for this model, this old, is around 15-16 mpg) and, upon inspection, realized that the rear driver wheel was harder to move, with the vehicle jacked up, than the other wheels. I suspected brake dragging. The truck had experienced low mileage for several months, so I suspect this problem has been going on for a while.
The first test I did was to jack up that wheel and remove the caliper. The hub now turned as easily as the other wheels. I thought it might be a case of sticking caliper piston or perhaps the caliper pins and their housings were filled with sticky/dried gunk interfering with the intended “floating” the caliper needs in order to adjust to wheel/suspension movement.
Since my rear brake pads were due for replacement, I got a new set of ceramic ones, a large tube of silicon based lubricant (Sil-Glyde) and got down to business. I found that the caliper bolts/pins and their boots and housings were full of dried-up gunk, so I meticulously cleaned everything with brake fluid (and with a small screwdriver for the housings), and lubed all the appropriate spots with Sil-Glyde. After applying Sil-Glyde, a lot of gunk came out attached to the screwdriver blade and the the pins finally moved freely inside their housings. The hub, I checked it again, turned easily by hand after getting the caliper off. The caliper piston was very easily compressed all the way in by use of a C-clamp. Both inner brake pads on the rear axle were similarly almost completely worn out, while the outer brake pads were similarly worn out half the way.
Now, after installing the new pads and lubing where appropriate, I reinstalled the caliper. One thing I noticed while tightening (the last few turns) the caliper bolts on the rear driver side caliper was that there was a noise from the rotor as if it was being tightly blocked (something similar to the noise from pulling a parking brake lever when the parking brake is in good working order, I thought).
Please note: the caliper piston at this time was still all the way in its housing, so it is definitely not a case of the caliper sticking. After mounting the tire (with the vehicle still jacked up and the caliper piston still all the way in its housing – at this time I hadn’t applied the brake pedal yet), I tried rotating the wheel and it was so tight that I could only move it very slowly by applying a lot of force with my hands…it was much tighter than ever before with the old, worn-out brake pads installed. Almost completely stuck.I drove the truck a couple of miles with the new brake pads installed and then touched the bolts on the four wheels to test for high temperature (indicative of brake dragging)..and found that the bolts on the rear driver side wheel were blazing hot! Something is definitely causing that wheel to be stuck and to generate all that friction.
So, if the caliper is not sticking, and the caliper pins are cleaned and lubed and freely “floating”… it would appear the culprit could very well be the parking brake cable being stuck causing the “e-brake” to drag. But then, again, if it is the parking brake to be at fault, why did the rotor get stuck upon tightening the caliper bolts? Could there be a connection between the action of tightening the caliper bolts and the parking brake exerting more friction against the rotor drum?
The parking brake hasn’t worked properly (producing only a very light braking action, with the parking lever in the cab feeling pretty loose when pulling it) since I bought this truck two and a half years ago, so I’ve used it rarely…maybe this lack of use has compounded the problem over time? I remember one instance, it was last year, when I drove with the parking brake lever pulled up (for no farther than a hundred yards or so), perhaps knowing this could be helpful.
What could be the cause and how do I go about testing the various possibilities? Suggestions and directions would be much appreciated.
Looking forward to your comments on this..[/size]
-
Replies
-
When you reset the caliper I believe you have to turn the piston to reset it?
Check that the pad clips are fully seated in the piston and the notches must
be 1200 and 600 o’clock for the pads to fit correctIt sounds like you might have a bad caliper. It may be binding up internally. More info here.
http://www.ericthecarguy.com/faq/solving-brake-problems
Please keep us updated on what you find.
[quote=”college man” post=152005]When you reset the caliper I believe you have to turn the piston to reset it?
Check that the pad clips are fully seated in the piston and the notches must
be 1200 and 600 o’clock for the pads to fit correct[/quote]That applies for the older 1st Gen Troopers. I have a 1994 (2nd Gen) where the piston doesn’t turn, it is just pushed straight in.
[quote=”EricTheCarGuy” post=152023]It sounds like you might have a bad caliper. It may be binding up internally. More info here.
http://www.ericthecarguy.com/faq/solving-brake-problems
Please keep us updated on what you find.[/quote]
Thank you, Eric, I’m going there to read right now.
[quote=”EricTheCarGuy” post=152023]It sounds like you might have a bad caliper. It may be binding up internally. More info here.
http://www.ericthecarguy.com/faq/solving-brake-problems
Please keep us updated on what you find.[/quote]
Eric, I read the “How to diagnose a bad brake caliper” page plus watched your video. First of all, I’m really impressed with the clarity and thoroughness of your video. I assume all other videos are of same quality. Thanks so much for making them and for maintaining this great website – it is a goldmine of precious information for the DIY’er, I’m so glad I’ve found it! 🙂
Now, as far as my caliper being a bad one.. This is my thinking, after reading your info and watching your video:
1) It could not be dirty caliper pins/housings, since I cleaned them well and lubed everything well with silicon paste.
2) Caliper piston went in quickly and easily (and brake fluid came out the same way from bleeder valve) when I used a C-clamp to push it in, just as easily as with the other caliper on the other side of the rear axle. So no indication of bad caliper here.
3) Inner brake pads had same amount of wear on both rear calipers, and outer brake pads also had same amount of wear, so no difference here between the supposedly bad caliper and the good one.
4) I would like to emphasize the fact that when I tightened the caliper bolts on the bad side (thus somehow binding the rotor), the caliper piston was still all the way in in its housing (I hadn’t pushed on the brake pedal yet), so a faulty caliper piston is out of the question also on this point.I’m thinking, how could the caliper otherwise be “binding up internally?” The caliper came out easily (just using my hands with no real effort) when I took it out after removing the two bolts, and went in the same way, super easily, when I put it back after installing the new brake pads. All was aligned perfectly.
And, once again, when tightening the caliper bolts started binding the rotor, the caliper piston was all the way in. I am really puzzled about this.I checked the caliper mount bracket, and it seems fine. I thought that it could perhaps be a case of bent caliper mount bracket? but it doesn’t appear so.
What else makes any sense in this scenario…could it be that the rotor is somehow not in its proper position, somehow displaced by something and being pushed outward? Or could it be that my axle/hub has moved outward? That’s all I can think of, aside from the possibility of a bad caliper, which, to me, doesn’t seem the case here.
Before going through the expense of getting new calipers, I’d like to consider other possible causes, given the above reasoning.
Please let me know if you see any faulty thinking on my part here. I much value your opinion, your talent and your experience.
I’d inspect the calliper mount bracket, if not attached correctly or something is padding it out from the hub assembly, that could cause your issues….
Maybe taking it off and wire brushing it and the mount may help?Chris.
[quote=”ChrisKaye” post=152041]I’d inspect the calliper mount bracket, if not attached correctly or something is padding it out from the hub assembly, that could cause your issues….
Maybe taking it off and wire brushing it and the mount may help?Chris.[/quote]
Thanks Chris for your advice. I’ll look into it. I’ll also take the time this time around to look closely at things and see if I can notice something not quite right that perhaps has escaped my attention before, and then report back with my findings.
Is it the rotors that have the drum parking brake fitted inside the rotor.? I would lube that parking brake cable real good and pull on it until it is freed and working.
…by installing a large washer on the caliper bolt that was getting the rotor stuck. Or at least it seems that way, so far.
I’m updating this thread today after receiving and installing some brand new rear caliper bolts I purchased online. I was hoping that replacing the old caliper bolts (which were identical on my truck) with what seemed to be more appropriate bolts – guide bolts (with the “flats”) on top and lock bolts (shorter ones with the rounded off tip) on bottom, as per the FSM – would solve the problem, but it did not.
Later, upon looking very closely at the various components and feeling quite a bit frustrated about the whole thing, I observed that there was noticeable wear on the bottom part of the brand new driver side rear caliper inner brake pad, which wear took just a short 2-mile trip to produce, after installing the new pads. Since it was the bottom caliper bolt on that side to get the rotor stuck upon tightening…it occurred to me to try and install a large washer (3mm thickness) on that bolt, and doing this instantly solved the problem! 🙂 With the washer installed, the bottom (lock bolt) on that caliper can now be tightened up all the way and it no longer gets the rotor stuck. My reasoning is that somehow there must be something inside that bolt housing that prevents the bolt from going all the way in without pushing on the outer wall of the caliper bolt housing and thus causing the bottom part of the inner brake pad to be pressed against the rotor. I don’t see how else this could be happening.. Perhaps the culprit could be a broken screwdriver blade tip or other foreign object left stuck in there by someone trying to clean the housing before I bought the truck? Any opinions on this?
I’ll drive it this way for a while and see if this is a permanent fix. I don’t think this should be causing a safety issue. Any feedback from you, as usual, will be much appreciated. I hope this helps someone reading this thread who is going through a similar challenge.
On a side note, though I tried hard (by hitting a piece of wood placed on the rotor with a hammer, and also by loosening the adjust nut on the parking brake equalizer), I haven’t been able to get the rear driver side rotor to come out. Anyway, the parking brake isn’t dragging, since after installing the washer on the bottom caliper bolt the wheel turns now freely as the one on the other side and the ones on the front of the vehicle.
Eric, you were right, after all, when you stated:
[quote=”EricTheCarGuy” post=152023]It sounds like you might have a bad caliper. It may be binding up internally.
Please keep us updated on what you find.[/quote]
I would disconnect the ebrake cable and zip tie it out of the way temporarily to see if that fixes it. It may have rusted internally. If that doesn’t fix it, try a brake fluid flush to make sure no contaminants from the fluid are causing the caliper piston to bind. Also, are the rims stock? If they are aftermarket the offset can be wrong for your truck can cause binding too.
[quote=”peshewa” post=152598]I would disconnect the ebrake cable and zip tie it out of the way temporarily to see if that fixes it. It may have rusted internally. If that doesn’t fix it, try a brake fluid flush to make sure no contaminants from the fluid are causing the caliper piston to bind. Also, are the rims stock? If they are aftermarket the offset can be wrong for your truck can cause binding too.[/quote]
As I wrote in my last post, it is all solved now. The wheel rotates easily now, no longer stuck. The washer I added has fixed the problem.
I have explained in this thread that it was not the caliper piston to bind, because the rotor used to get stuck (by inner brake pad) upon tightening the caliper bolts when the piston was still fully retracted (fully back in its housing). Now, after adding the large washer which prevents the lower (lock) caliper bolt/pin from going all the way in, it no longer does and everything works just fine. I still think that the obvious explanation is that something inside the lower caliper pin housing in that caliper prevents the pin from going fully in without pushing the caliper outwardly…which is what was causing the rotor to get stuck before. All good now, though. 🙂
The parking brake is not interfering either with the free rotation of that wheel previously stuck. I drove the truck 100 miles or so yesterday, no problem.
The only thing that remains to be fixed is to get the parking brake to exert more braking power. I also, in the long run, will need to get the rotor to come out when I need to replace rotors…but nothing urgent. Again, the rotor is no longer bound, the wheel is moving freely and the truck can be driven normally.
- You must be logged in to reply to this topic.